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TR-20 DOS version


Having been superceded by WinTR-20, this DOS version is still being made available, but no longer supported.  Technical Release No. 20: Computer Program for Project Formulation Hydrology (TR-20) is a physically based watershed scale runoff event model. It computes direct runoff and develops hydrographs resulting from any synthetic or natural rainstorm. Developed hydrographs are routed through stream and valley reaches as well as through reservoirs. Hydrographs are combined from tributaries with those on the main stream stem. Branching flow (diversions), and baseflow can also be accommodated.


The Hydrology Branch of the SCS (forerunner of NRCS) in cooperation with the Hydrology Laboratory (ARS) developed the original FORTRAN computer program through a contract with C-E-I-R, Inc. in 1964. The original version ran on an IBM 1620 mainframe computer. The SCS Engineering Division made numerous modifications over the years, and a PC version of the program came out with a draft User Manual in 1986. Further revisions to both the program and user manual resulted in version 2.04 and 1992 draft user manual.

These files require a zip utility or Adobe Acrobat.

TR-20, Version 2.04 package,  (254 Kb)
February 1992 Draft Users' Manual, tr-20.pdf  (12.3 Mb)
Hydrology Technical Note 2  (1.5 Mb)

The Natural Resources Conservation Service used government funds to develop the Technical Release 20 (TR20) computer program. It may be downloaded for use and copying at no additional expense or license requirements.

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